NEEDING to study the ignition characteristics of Diesel-engine fuels, the authors developed an idea that was presented at a meeting of the Research Committee of the Society last June. The idea was that engine tests must be the basis of evaluation. A C. F. R. engine was converted into a variable-compression Diesel engine by substituting a new piston and a fuel-injection system for the original piston and ignition system.
Test methods that have been developed are reported, together with some results that show the practicability of the procedure and its substantial agreement with data secured in other ways. It is suggested that, as some of the most desirable qualities of gasoline are undesirable for Diesel fuel, and vice versa, fuels may be divided in the future on that basis, and Diesel and gasoline engines may approach each other in compression ratio.
Discussers are warm in their appreciation of the work reported, one of them describing it as the most fundamental work on fuels since the development of the bomb test. Another discusser reports work on gasoline with a C. F. R. engine in which the electric ignition was not used and the autoignition temperature was determined by increasing the compression to the point at which autoignition occurred. That point was found to be quite definite and to check well with data in the paper.